GB2309687A

GB2309687A - Jam prevention in sheet supply

Info

Publication number: GB2309687A
Application number: GB9701845A
Authority: GB
Inventors: Terrence Lee Fisher
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1996-02-01
Filing date: 1997-01-29
Publication date: 1997-08-06
Also published as: DE19701052A1; JPH09220833A; GB9701845D0

Description

2309687 JAM PREVENTION FOR CUT SHEET SUPPLY

BACKGROUND OF THE INVENTION

Technical Field

This invention relates generally to a imaging apparatus wherein a plurality of cut sheets are stacked in a supply to be driven from the supply to be imaged, and more particularly to such apparatus wherein the sheets are at least partially returned to the supply during the imaging process.

Background Art

Copiers, printer, facsimile apparatus and similar imaging machines are often provided with a cut sheet tray from which sheets are fed, such as by a scuff roller. As used herein, the term "tray" shall include removable sheet holders and fixed bin sheet holders. The cut sheets may be used such as for originals to be reproduced or as receiver sheets to be imaged. In this specification and appended claims, the convention will be used that the sheets are stacked in the tray such that the "leading edge" of the sheets will be the first edge to emerge from the tray, and that the "trailing edge" of the sheets will be the last edge to emerge.

In a commercial thermal printer, the cut sheets travel downstream, leading edge first, from the tray to a printhead, where the sheets receive one of a plurality of color separation images. Before receiving each subsequent color separation image, the sheet is returned trailing edge first to a position upstream of the printhead. Because there is insufficient distance between the tray and the printhead for an entire sheet, the trailing edge of the sheet returns to a position inside of the cut sheet tray.

It has been found that, from time to time, jams may occur during the sheet-return process; particularly as the trailing edge of the sheet attempts to move past the leading edge of the stack of sheets remaining in the cut sheet tray.

DISCLOSURE OF THE INVENTION it is an object of the present invention to reduce the risk of jams that occur during return of a cut sheet to a position inside of the cut sheet tray as the trailing edge of the sheet moves past the leading edge of the stack of sheets remaining in the cut sheet tray. It is another object of the present invention to reduce the risk of jams that occur during return of a cut sheet to a position inside of the cut sheet tray by covering the jam area during the return of the cut sheet and uncovering the jam area during feeding of a cut sheet from the stack of sheets in the cut sheet tray.

It is still another object of the present invention to reduce the risk of jams that occur during return of a cut sheet to a position inside of the cut sheet tray by moving a lever to a position over the jam area when the cut sheet is returning to the tray, and moving the lever to a remote position during feeding of a cut sheet from the stack of sheets in the cut sheet tray.

According to a feature of the present invention, imaging apparatus, which has a sheet path and a supply for receiving a stacked plurality of cut sheets for feeding one at a time from the supply along the sheet path, includes a device for at least partially returning a cut sheet to the supply past an edge of any other cut sheets remaining in the supply.

A member has a first position covering the edge of the cut sheets in the stack. The member is moved to its first position during the return of the cut sheet to the supply, whereby the edge of the other cut sheets in the stack does not interfere with the cut sheet being returned to the supply.

According to another feature of the imaging apparatus, the member has a second position removed from the sheet path, whereby to not interfere with 10 sheets being fed from the stack.

According to a preferred embodiment of the imaging apparatus of the present invention, the member is a comb-shaped lever having a plurality of arms which cover the edge of said any other cut sheets when the 15 member is in said first position.

The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which:

Figure 1 is a perspective assembly view of a cut sheet supply tray according to the prior art;

Figure 2 is a view of the cut sheet supply tray of Figure 1 showing a sheet being fed from the stack; Figure 3 is a view of the cut sheet supply tray of Figure 1 and associated imaging apparatus, showing a sheet being attempted to be returned to the stack; Figure 4 is a side sectional view of a cut sheet supply tray and associated imaging apparatus according to the present invention; Figure 5 is a perspective view of a detail of 5 the cut sheet supply tray of Figure 4; Figure 6 is a perspective assembly view of the cut sheet tray and imaging apparatus of Figure 4; Figure 7 is an enlarged detail view of a portion of the cut sheet tray and imaging apparatus of 10 Figure 6; Figure 8 is a side schematic view of the cut sheet tray and imaging apparatus of Figure 6 showing the cut sheet supply tray and the imaging apparatus in a second operational state; Figure 9 is a side sectional view of a cut sheet supply tray and associated imaging apparatus according to another embodiment of the present invention; Figure 10 is an enlarged detail view of a 20 portion of the imaging apparatus of Figure 9; Figure 11 is a side schematic view of the cut sheet tray and associated imaging apparatus of Figure 9 showing the cut sheet supply tray and the imaging apparatus in a second operational state; Figure 12 is a side sectional view of a cut sheet supply tray and associated imaging apparatus according to yet another embodiment of the present invention; Figure 13 is a side schematic view of the cut sheet tray and associated imaging apparatus of Figure 12 showing the cut sheet supply tray and the imaging apparatus in a second operational state; Figure 14 is a perspective assembly view of the cut sheet tray and associated imaging apparatus of Figure 12; and Figure 15 is a perspective view of a portion 5 of the cut sheet tray of Figure 12.

BEST MODE FOR CARRYING OUT THE INV=ION

The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. While the invention is described below in the environment of a removable tray for image receiver sheets, it will be noted that the invention can be used with other types of devices for stacking a large plurality of cut sheets where a sheet that has been removed from the stack must be at least partially returned to the stack.

Referring to Figure 1, a tray 10 having an open top is adapted to receive a stack of cut sheets for supply one at a time to a machine, such as for example an imaging apparatus. The sheets may be original documents to be reproduced or blank sheets upon which an image is to be received. The leading edges of the sheets of the stack are located against corner abutments 14 and 16. The side edges of the sheets of the stack are aligned by a fixed edge guide 18 and a laterally-adjustable edge guide 20, while the rear edge of the sheets of the stack are positioned by a movable rear guide 22.

Figure 2 shows a sheet 12 being fed from the stack by a picker roller 24. The leading edge of the sheet rides over a front tray surface 28 to a sheet -6 guide 3 0. Sheet guide 30 directs sheet 12 to a printhead, not shown. After the sheet has been imaged with one of a plurality of color separations, it is returned to the upstream side of the printhead. During this return process, the trailing edge of the sheet must enter tray 10. As can be seen in Figure 3, there is a risk that the edge of the sheet may engage the edge of the stack of sheets remaining in the tray; causing a jam condition.

Figures 4 to 6 show a comb-shaped lever 34 that has a pair of arms 36 and 38 mounted in tray 10 at pivot points 40 and 42, respectively. Lever 34 has a plurality of guide arms 44, 46 and 48 and an abutment 50, best seen in Figure 5. As shown in Figures 4 and 6, arms 44, 46 and 48 extend through a series of holes in the front tray surface 28. The liver is biased by a spring 52 to a position shown in Figure 4, whereat guide arms 44, 46 and 48 cover the leading edge of the stack of sheets 12 remaining in the tray, preventing a jam condition as a sheet 12 re enters the tray.

Referring to Figures 7 and 8, a solenoid 54 can be selectively activated to rotate lever 34, removing guide arms 44, 46 and 48 from the sheet path when picker roller 24 is operated to remove a fresh sheet from the stack.

In the previously-described embodiment of the present invention, lever 34 was operated be solenoid 54. However, the lever can also be controlled by association with a mechanical feature of the printer that moves between two spacedapart positions in the sheet feed stage and the sheet return stage of the print cycle.

For example, many commercially available dye transfer thermal printers have a capstan roller pair which, during the printing phase, is in a closed position. During the phase of the apparatus in which the receiver sheets are returned to the upstream side of the printhead, the capstan roller pair open to release the receiver sheets. According to a feature of a second embodiment of the present invention illustrated in Figures 9 to 11, a crank arm 72 is rotatably mounted about a pivot 74.

One end 76 of crank arm 72 is journalled to the movable roller of the capstan pair, so that the crank arm rotates in the counter clockwise direction as illustrated, to the position shown in Figure 9 when the capstan pair is closed for the printing phase. The other end 78 of crank arm 72 carries a pin 80 which rides along a slot 82 in a lever 84.

Lever 84 pivots about a stud 86 and has a projection 88. The lever is best shown in Figure 10.

When crank arm 72 is in the position illustrated in Figure 9, projection 88 clears comb-shaped lever 90; allowing the lever to swing about pivot 92 to allow receiver sheets 12 to be fed from tray 10.

Referring now to Figure 11, crank arm 72 rotates in the clockwise direction, as illustrated, about pivot 74 to the position shown in Figure 11 when the capstan pair is opened during the phase of the apparatus in which the receiver sheets are returned to the upstream side of the printhead. The other end 78 of crank arm 72 causes lever 84 to pivot about stud 86 so that projection 88 lifts comb-shaped lever 90 about pivot 92 to direct returning receiver sheets above the sheets remaining in tray 10.

Figures 12 to 15 are schematic views of still another embodiment of the present invention, wherein comb-shaped lever 34 is operated by picker roller 24 of the imaging apparatus. Referring to Figure 12, when a sheet 12 is being picked from the stack, picker roller 24 moves to a first position where it presses against the stack of sheets, and (as shown in Figure 14) a disk 94 presses against one or more pivotally- mounted intermediate levers 88 that cause the comb-shaped lever 34 to uncover the stack of sheets so a sheet can move into the media transport path. When the sheet has successfully entered the media transport path, picker roller 24 moves to a second position away from the stack of sheets, as illustrated in Figures 13 to 15. This permits a tension spring 96 to rotate intermediate lever 88, causing comb-shaped lever to cover the stack of sheets to prevent jams.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

What is claimed is:

1. Imaging apparatus having a supply of cut sheets for feeding along a sheet path, and means for at least partially returning a cut sheet to the supply past an edge of any other cut sheets remaining in the supply; characterized by a member having a first position, covering the edge of said any other cut sheets, and a second position, removed from the sheet path, whereby to not interfere with sheets being fed from the stack; the member being moved to said first position during the return of the cut sheet to the supply, whereby the edge of said any other cut sheets does not interfere with the cut sheet being returned to the supply.

2. Imaging apparatus as set forth in claim 1, wherein the member is a comb-shaped lever.

3. Imaging apparatus as set forth in claim 2, wherein said comb-shaped lever has a plurality of arms which cover the edge of said any other cut sheets when the member is in said first position.

4. Imaging apparatus as set forth in claim 1, wherein the returning means returns the cut sheets to the supply along the sheet path.

5. Imaging apparatus as set forth in claim 1, wherein the cut sheets have opposed leading and trailing edges, the sheets being fed from the supply leading edge first and returned to the supply trailing edge first.

6. Imaging apparatus as set forth in claim 1, wherein the supply is a removable tray having a surface over which sheets are fed from the tray to the sheet path.

7. Imaging apparatus as set forth in claim 6, wherein the member is a comb-shaped lever having a plurality of arms which extend from the tray surface to cover the edge of said any other cut sheets when the member is in said first position.

8. Imaging apparatus as set forth in claim 1, further comprising spring means for biasing said member toward its first position.

9. Imaging apparatus as set forth in claim 1, further comprising a motor for moving the member to at least one of said first and second positions.

10. Imaging apparatus as set forth in claim 1, wherein: the apparatus includes a mechanical feature that moves between two spaced-apart positions during an imaging cycle such that (i) the feature is in one of said spaced-apart positions during feeding of a cut sheet from the supply and (ii) the feature is in the other of said spaced-apart positions during return of a cut sheet to the supply; and movement of the member is associated with the position of the mechanical feature.